1. Field of the Invention
This invention relates to a composition for use in the oral cavity. More particularly, it relates to a composition for use in the oral cavity comprising granules which have a specified apparent density and which collapse at predetermined deformation rate values so as to make users feel the cleaning effect of the composition by the tactual sense of the granule in the oral cavity. Moreover, the composition gives a pleasant feeling to users.
2. Description of the Background Art
Various compositions for use in the oral cavity are well known which comprise granules or granular materials. These granules or granular materials sometimes contain pharmaceutical ingredients such as drugs and enzymes, or they are incorporated into a composition to give the composition an attractive appearance. The size and hardness of granules are determined depending upon the purpose of use of the granules. For example, the size and hardness of granules may be so determined that users can realize, by tactual sense in the oral cavity, that the plaques on the teeth is being removed as the granules collapse to finally give no tactual sense of the granules. In another example, the granules are so designed that they do not give any tactually conceivable feel to users from the beginning, but only gives an aesthetic effect to the products to improve the appearance thereof.
In the processes of preparing such granules, a binder which includes a water-soluble material and a water-insoluble material has been used.
An example of the water-soluble material conventionally employed in the preparation of the granules is a water-soluble high molecular compound such as carboxymethylcellulose or methylcellulose. Granules prepared with such water-soluble binders, however, have a disadvantage in that their hardness significantly decreases when they are incorporated into a composition for use in the oral cavity such as a tooth paste which includes water. This causes collapse of the granules during the preparation process. Even when the granules can keep their granular shapes during the preparation process, the granules cannot be felt in the oral cavity, because the granules are softened due to contact with water. Accordingly, users cannot feel the presence of the granules and the cleaning effect thereof.
Examples of a preparation process using a water-insoluble material include a process disclosed in Japanese Laid-Open Patent Application Nos. 49-132249 and 50-81594 in which a wax is used as a water-insoluble binder to bind abrading agents for obtaining granules, and a process disclosed in Japanese Laid-Open patent Application No. 58-126806 in which abrasive agents are combined to form granules with ethylcellulose, which is water-insoluble but ethanol-soluble. However, granules prepared by these methods are still not satisfactory, because users cannot feel the granules very well in their oral cavities. When the amount of the binders is increased, the hardness of the granules increases, which makes users clearly feel the presence of the granules. In this case, however, collapsibility of the granules tends to be deteriorated, because a plastic deformation occurs instead of a brittle collapse when the amount of the binders increases. As a result, these granules give users an unpleasant feeling in that the granules stick to or are stuck between the teeth.
Thus, there has been a demand for a composition for use in the oral cavity which meets the following two requirements: gives a pleasant feeling to users; makes users feel the cleaning effect of the composition.